Apparatus for object information detection and methods of using same

ABSTRACT

A method for detecting an object on a sensor sensitive to capacitive coupling comprises simultaneously transmitting signals on at least two electrodes of the sensor, wherein at least one of the signals transmitted on each of the at least two electrodes has a frequency that is different from a frequency of at least one other signal transmitted on another electrode of the at least two electrodes, sampling a signal on at least one other electrode crossing the at least two electrodes, wherein the signal is responsive to capacitive coupling formed between the at least two electrodes and the at least one other crossing electrode, and detecting at least one object from the sampled signals.

RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.11/463,788, filed on Aug. 10, 2006, which claims the benefit under 35U.S.C. §119(e) of U.S. Provisional Patent Application No. 60/707,339,filed Aug. 11, 2005, the disclosure of which is incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates generally to detecting information aboutobjects. For example, an apparatus is provided which, as one of itsfunctions, optionally detects position, identification and/ororientation information pertaining to objects located on the apparatus.

BACKGROUND OF THE INVENTION

Numerous methods have been used to detect information about objects, inparticular about small objects placed on a surface. The following is byno means a complete review of the field, but rather describes a numberof references that illustrate the state of the art.

U.S. Pat. No. 6,690,156, the disclosure of which is incorporated hereinby reference, describes a system for identifying and determining theposition of game pieces on a game board. One of the methods describeduses an excitation coil surrounding the sensor to excite circuitry inthe game pieces at its resonant frequency and a sensor on top of theboard to acquire signals that are generated by the game pieces inresponse to the excitation. Based on the excitation and response, theposition and identification of the game piece is determined.

US Patent Application Publication No. 2004/0095333, the disclosure ofwhich is incorporated herein by reference, describes a tablet with astructure of orthogonal conductors immediately beneath the tabletsurface but on top of a display screen. The tablet also includes a coilsurrounding the surface. In operation, a stylus comprises a resonantcircuit which is excited by the surrounding coil. A signal generated inresponse, by the stylus, is acquired by the conductors and is detected.Based on the presence of signals in some of the conductors, the presenceand position of the stylus is determined. It is noted that while thisreference deals mainly with a stylus and a tablet, the use of the systemto determine information regarding game pieces (paragraph 116) is alsosuggested.

US Patent Application Publication No. 2004/0155871, the disclosure ofwhich is incorporated herein by reference, describes a variant on thesystem of the previously discussed reference. In general, a dual purposetablet is described utilizing the same general tablet structure as theprevious reference. However, in a series of embodiments, the structurecan be modified to also determine the presence of a finger on thesurface using the same sensor used for the stylus' detection. In thesecond of these embodiments (described in paragraphs 163-174 and FIGS. 2and 3) a signal is fed into conductors that lie in one direction. Thefinger introduces capacitive coupling between the orthogonal lines sothat a signal is detected in those orthogonal lines that are adjacent orbeneath the finger. This detected signal is used to determine thepresence and position of the finger.

It is noted that each of these references describes using transparentconductors, such that the sensor can overlay an imaging screen such asan LCD screen.

Each of these references includes an extensive review of the prior artin the background section, which is not repeated here. However, thisreview is incorporated by reference together with the rest of thesedocuments.

SUMMARY OF THE INVENTION

An aspect of some exemplary embodiments of the invention relates toproviding an apparatus and/or method for detecting an object informationcode which is linked to information regarding at least object located onthe apparatus based on capacitive coupling between elements of theapparatus that is caused or changed by presence of the object. In anembodiment of the invention, the object is a passive object. In someembodiments of the invention, the object information code is the signaloutput from the apparatus as a result of the capacitive coupling withthe object when a signal is input to the apparatus.

In some exemplary embodiments of the invention, the apparatus comprisesa planar board or tablet on which the objects are situated.

In some exemplary embodiments of the invention, information includes theposition of the object.

In some exemplary embodiments of the invention, information includes theidentification of the object. Optionally, the object information code isdetected from a geometric arrangement of tokens on the object.Optionally, the object information code is detected using at least oneconductive (or more generally, capacitive) token (e.g., small regions ofconductive material associated with a detection surface of the object)or a pattern of tokens located on the object having varying conductivityand/or number and/or spatial arrangement and/or varying conductivesignature. In some exemplary embodiments of the invention, the objectinformation code is detected from a pattern of conductive materiallocated on the object having varying conductivity. Optionally, theobject information code is detected using a pattern of tokens located onthe object having varying size and/or number and/or varying distancebetween tokens. It should be understood that in some embodiments of theinvention, a particular object is not restricted to tokens of a specificsize and/or number and/or distance between the tokens, as all of theseare variable on the object in order to provide a broad range ofidentification possibilities for the object. In some exemplaryembodiments of the invention, the object is transparent and comprisestransparent conductive tokens.

In some exemplary embodiments of the invention, information includes theposition of the object. This position is optionally determined byidentifying the strongest signal detected by junctions in a sensor array(described below) and then approximating distance from that junction.Optionally, passive reception of a signal on at least one neighboringjunction to the object is also used for determining the center of theobject. Optionally, the center is detected by weighting an average ofsignal detections. Optionally, a look-up table is used to correlatesignal measurements at a plurality of junctions in a sensor array to anapproximate location of an object center. Optionally, the center iscalculated by a combination of the methods. Optionally, the center iscalculated by averaging the results obtained from the described methods.

In some exemplary embodiments of the invention, information includes theorientation of the object. The objects' orientation and position areoptionally detected continuously. Optionally the orientation isdetermined by detecting an orientation of a pattern of tokens on theobject.

In some exemplary embodiments of the invention the object informationcode is a “security” code which can be associated with a set of objectsto be used with a particular copy of software. For instance, all objectssold with the copy of software will have a distinctive pattern, which isknown by the copy of software, thus, attempts to copy the software anduse it with other objects (e.g. objects which are not associated to thatspecific copy of software) will not be successful.

In some exemplary embodiments of the invention, one or more objectscontain circuitry that transmits a secure object information code to thetablet. This can provide an additional level of security, for example,if the software associated with the objects will not run in the absenceof the code. Optionally, a USB security device can be used toenable/disable the software.

Security can also be provided by an RFID tag that may reside in or onthe object. If this type of security is provided, the system willrequire an RFID reader.

In some embodiments of the invention, the objects are hand held objects.In other embodiments, the objects move autonomously on the surface andmay be controlled by a controller via a wired or wireless connection.For example, the objects could be in the shape of a car and bemotorized.

In some embodiments of the invention, movement of the objects iscontrolled by a robotic device controlled by a host or remotely via theinternet.

In some embodiments of the invention, the object is a body part.

In some exemplary embodiments of the invention, the apparatus canrecognize the presence of a finger or hand even when the finger or handdoes not actually touch the surface. This allows for a non-contactingfinger to move a cursor and, optionally, when the cursor is in a desiredposition, for finger contact with the surface to be identified in thesame way as a mouse click. Optionally a double finger tap or a prolongedduration of contact on the surface is identified as a right click of amouse. If the prolonged tap is used as a right click, then a double tapcould represent a double click.

In some exemplary embodiments of the invention, the apparatus forinformation detection is comprised of a sensor module situated at orimmediately beneath the surface, a controller section and/or a hostsection. Optionally, the sensor module includes a sensor array, forexample an array of elongate transparent electrodes, adapted andconstructed to detect information regarding at least one object locatedon the surface. Optionally, the controller section provides an interfacebetween the sensor section and the host section. Optionally, the hostsection processes information gathered by the sensor module and providesan output of processed information.

In some exemplary embodiments of the invention, the apparatus displaysimages. Optionally, the images are displayed on a display screensituated below a surface on which the object is placed and below thesensors that sense the objects or fingers.

In some exemplary embodiments of the invention, the surface functions asa game board and the object is a gaming piece. Optionally, the objectrepresents a player or object taking part in the game.

In some exemplary embodiments of the invention, the object is a stylus.In other embodiments the object can be a game piece (such as a pawn froma chess game), a pointing device (such as a mouse), a card a transparentframe or virtually any physical element that interacts with the sensor.

An aspect of some embodiments of the invention is concerned with anapparatus having a plurality of functions. Optionally one of thefunctions is to determine the position and optionally the orientationand/or identity and/or the shape or contour of an object on a surface asdescribed above. The objects can be game pieces, a stylus, or otherobjects whose position is to be determined Optionally one of thefunctions is to determine the position of one or more fingers or thecontour of a user's palm or hand or other body part on the surface.Optionally one of the functions is to enable the detection ofmulti-touch on the surface. Optionally one of the functions of theapparatus is to operate as a computer, with the surface optionallyoperating as the display screen of the computer. Optionally, the displayfunctions as a tablet, with the object being a stylus or othercapacitive object.

An aspect of some exemplary embodiments of the invention relates to amethod for distinguishing the presence of a capacitive portion of anobject (sometimes hereinafter a “token”) from a finger. By using thediffering electrical responses of a sensor array to touch by an objector a body part (such as a finger) respectively, analysis of theseresponses can optionally provide identification of the two.

There is thus provided in accordance with an exemplary embodiment of theinvention, a system for determining information regarding at least oneobject, comprising: a sensor sensitive to capacitive coupling; at leastone object adapted to create a capacitive coupling with the sensor whenat least one signal is input to the sensor; a detector adapted tomeasure at least one output signal of said sensor associated with the atleast one object, wherein the output signal associated with the at leastone object is an object information code. Optionally, the at least oneobject is provided with a pattern of conductive areas containing theobject information code. Optionally, the pattern of conductive areas iscomprised of conductive tokens. Optionally, the pattern of conductiveareas includes conductive and non-conductive areas to provide a binaryobject information code. Optionally, the pattern of conductive areas iscomprised of differently sized conductive areas such that some areascause a different capacitive coupling than other areas. Optionally, thepattern of conductive areas is comprised of conductive areas, of whichat least a first conductive area is located a first distance from asecond conductive area which is located a second distance from at leasta third conductive area. Optionally, the first and second distances areselected from a set of predefined different distances. Optionally, atleast two of the conductive areas are selectively in conductiveconnection with each other. Optionally, the pattern of conductive areasforms at least one of a plurality of rows, a plurality of columns or ageometric shape. Optionally, the information is at least one ofposition, identity, or orientation of the object on the sensor.Optionally, the measurement of said at least one output signal is atleast one of voltage, amplitude, phase, frequency, or correlation.Optionally, the sensor is comprised of two arrays of electrodes, a firstarray comprising a first set of electrodes and a second array comprisinga second set of electrodes. Optionally, the first and second arrays areorthogonal.

In some exemplary embodiments of the invention, the system furthercomprises a source of the input signal adapted to input the at least onesignal to the first set of electrodes; and, wherein the input signal istransferred to the second set of electrodes by the at least one objectcapacitively coupled to at least one of the second set of electrodes.

In some embodiments of the invention, the at least one object is one ofa plurality of objects, each with a different object information code.

Optionally, the at least one object is a game piece. Optionally, the atleast one object is a pointing device.

Optionally, a pointing device is a stylus or mouse.

Optionally, at least one object is a body part of a user.

In some embodiments of the invention, at least one object comprisesseveral surfaces, and wherein each surface comprises an informationcode. Optionally, at least one object is a gaming die.

In some embodiments of the invention, the system further comprises adisplay having an image that can be changed electronically displayedthereon. Optionally, the display underlies the sensor and wherein thesensor is substantially transparent.

In some embodiments of the invention, the system is a personal computer.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary non-limiting embodiments of the invention are described in thefollowing description, read with reference to the figures attachedhereto. In the figures, identical and similar structures, elements orparts thereof that appear in more than one figure are generally labeledwith the same or similar references in the figures in which they appear.Dimensions of components and features shown in the figures are chosenprimarily for convenience and clarity of presentation and are notnecessarily to scale. Referring to the following:

FIG. 1A is a perspective view of an air hockey game board surface, inaccordance with an exemplary embodiment of the invention;

FIG. 1B is a view of how a game of tennis would appear to the user, inaccordance with an embodiment of the invention;

FIG. 1C is an exterior perspective representation of a game board, inaccordance with an exemplary embodiment of the invention;

FIG. 2 is a generalized block diagram depicting an apparatus fordetecting information, in accordance with an exemplary embodiment of theinvention;

FIG. 3 is a block diagram depicting data flow in a sensor and acontroller, in accordance with an exemplary embodiment of the invention;

FIG. 4 is a general schematic diagram of a sensor electronics optionallyimplemented as an ASIC, in accordance with an exemplary embodiment ofthe invention;

FIG. 5 is a configuration of tokens located on an object, in accordancewith an exemplary embodiment of the invention;

FIGS. 6A-C show an object provided with at least one switch forselectably changing the conductive pattern of the object, in accordancewith an exemplary embodiment of the invention;

FIG. 6D shows an object provided with at least one switch and at leastone enlarged token for changing the conductive pattern of the object, inaccordance with an exemplary embodiment of the invention;

FIG. 6E shows an object which changes its conductive pattern byphysically moving at least one token, in accordance with an exemplaryembodiment of the invention;

FIG. 7A is an exemplary method for determining object and/or fingercontact, in accordance with an exemplary embodiment of the invention;

FIG. 7B is a graphic representation of a signal output indicating objectand finger contact, in accordance with an exemplary embodiment of theinvention;

FIG. 8 is an exemplary look-up table method for finding the center of atoken, in accordance with an exemplary embodiment of the invention;

FIG. 9 is an exemplary geometric method for finding the identification,orientation and/or position of an object, in accordance with anexemplary embodiment of the invention;

FIGS. 10 and 11 illustrate two different exemplary geometric structuresof token patterns usable in embodiments of the present invention;

FIG. 12 shows such a possible configuration in which two objects areclose enough so that there is ambiguity as to which objects are present;

FIG. 13 is a flow chart of a method for finding the identification,orientation and/or position of an object, utilizing varied conductivityor capacitance of tokens, in accordance with an exemplary embodiment ofthe invention;

FIG. 14 shows a simplified schematic layout of a system for providingmode change over for a sensor array, in accordance with an exemplaryembodiment of the invention;

FIG. 15 shows a sequentially activated sensor array, in accordance withan exemplary embodiment of the invention;

FIGS. 16A-B show distance sensitive identification patterns for anobject, in accordance with an exemplary embodiment of the invention; and

FIGS. 16C-D show binary sensitive identification patterns for an object,in accordance with an exemplary embodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1A shows a perspective view of an exemplary apparatus 100 forcollecting information regarding at least one object, an air hockey gameboard, in accordance with an exemplary embodiment of the invention. Theillustrated game board is purely exemplary and its external structureand features may vary from the board shown, for example as shown withrespect to FIGS. 1B and 1C. In a conventional air hockey arrangement,apparatus 100 for collecting information is provided with a plurality ofobjects including two goals, 102, 104 one at either end of the gameboard. Naturally, the object of the game is to score by getting anotherobject, a puck 106, into the opponent's goal 102 or 104 more often thanyour opponent up to some predetermined score. Puck 106 is typically hitusing other objects, paddles 108, 110, which are held in at least onehand by the players.

In an embodiment of the invention, a representation of the physical gameboard is shown on a display, optionally along with the real-timeinformation collected by apparatus 100 and related to puck 106, paddles108, 110, and optionally goals 102, 104 (which do not actually move inthis game). Optionally, the game board and/or objects used in the game,such as puck 106, are projected on a display located under a sensorarray (such as described below). Real-time information related to theseobjects includes at least one of position, velocity, orientation,identity and/or acceleration. In an embodiment of the invention,apparatus 100 detects at least some information related to an objectcontinuously. In some embodiments of the invention, apparatus 100detects output object information codes related to the objects which arethe result of an input signal applied to a sensor array (described belowand assigned reference number 203) above or beneath the game board. Inan embodiment of the invention, the object information codes correspondto information related to the objects, for example position,orientation, and/or identity.

FIG. 1B shows a representation 150 of a tennis game in accordance withan embodiment of the invention. As in the real world, the game includesa tennis court 152, including a net 154, a ball 156 and two players 158and 160. In the disclosed embodiment, all of the components of the gameare on the screen, except for the two players 158 and 160. As describedin more detail below, the apparatus for collecting information 100 isoptionally capable of not only identifying the game pieces anddetermining their position, but also of determining the orientation ofthe piece. Since the position and orientation can be determined within avery short time (e.g. in a fraction of a millisecond or less) thisallows for substantially continuous determination of these parameters.In an embodiment of the invention, apparatus 100 provides a very highresolution at least in position and orientation of the object, thereforehence even a small change of the object's position and/or orientation,only few mm in some embodiments of the invention, is detected (sensed)by sensor array 203.

In operation, in playing the illustrated tennis game, each player movesand rotates his or her game piece in order to place the racket at theball and also to rotate the game piece so that the ball is “hit” by theracket. The ball is moved, on the screen, responsive to a determinationby a computer host that the ball was hit and when and how it was hit.

This embodiment is provided for illustrative purposes to demonstrate howcontinuous determination of the position and orientation could be usedin a game and to illustrate, at least in part, the additional dimensionthat would be available to a game designer.

It should be noted that while games have been shown, other uses for sucha system will immediately occur, such as for use in command and controlsystems, education, simulation and training. The size, externalstructure, response time and resolution of the board may vary, dependenton the use for which it is intended.

FIG. 1C shows an exemplary apparatus for collecting information 180,illustrated in the form of a game board, in accordance with an exemplaryembodiment of the invention. The illustrated game board is purelyexemplary and its external structure and features may vary from theboard shown.

The illustrated game is a chess game with a plurality of game pieces 182(sometimes referred interchangeably as “objects”) and a game playingsurface 184 on which the objects 182 are placed. In an embodiment of theinvention the game pieces can be identified by sensing apparatus (notshown but illustrated with respect to a sensor section 202, below)situated at least partly on or beneath surface 184.

In some embodiments of the invention, surface 184 is the surface of, oroverlays, a display screen such that the game board layout can be easilychanged by software. In addition, provision of such a variable displayscreen allows for the display of one or more timers 186 and even thepicture 188 or other identification of the person whose move it is. Theboard can also provide an indication of an illegal move, for example, byflashing the square on which an illegally moved object 182 is placed orcan indicate a suggested move, for example, by lighting up a startingand ending square. It is also possible to play “against the machine”with the board indicating the place to which game pieces are to bemoved.

Optionally, two separate game boards can be connected. In an embodimentof the invention, one of the computers acts as a master and the other asa slave, or both are connected to a common host, although this is notcompulsory. This type of connection could be used, for example, to allowfor the playing of games in which the players do not see each othersgame boards, such as for example, a form of “naval battles.” Theconnection could be wired via a USB or RS 232 connection or the like orcan be wireless (Bluetooth or an IR connection, for example) or via theinternet.

Methods for connecting two tablets to a common host and in amaster/slave configuration are shown, for example in a U.S. patentapplication filed Jul. 14, 2005 entitled “Automatic Switching for a DualMode Digitizer by applicants Haim Perski and Ori Rimon, the disclosureof which is incorporated herein by reference.

Furthermore, the game boards do not have to be rectangular, althoughthis is often a convenient shape. Optionally, in some embodiments of theinvention, the game board may be curved. Optionally, the game surfacecan be made flexible to allow for a three dimensional appearance to thegames (for example in a racing game).

FIG. 2 shows a block diagram 200 of hardware sections which compriseapparatus for detecting information 100, in accordance with an exemplaryembodiment of the invention. Sensor section 202 is provided to anapparatus for detecting information 100, in some exemplary embodimentsof the invention, which includes a sensor array 203 (shown in FIG. 3)and is adapted and constructed to detect information regarding at leastone object 102 located thereon. An exemplary sensor section 202 isdescribed in more detail below.

Apparatus for detecting information 100 is also provided with anoptional host section 206, in some exemplary embodiments of theinvention. Host section 206 optionally processes information gathered bythe sensor section and provides an output of processed information, forexample to the surface 104 and/or to software configurable elements suchas those referenced by reference numbers 106 and 108 in FIG. 1A.Optionally, host section 206 displays images, optionally on (generallyunderneath) surface 104.

Optionally, host section comprises a separate display, such as a liquidcrystal display (LCD). Optionally, audio is provided to accompany theplay.

In some exemplary embodiments of the invention, host section 206functions as a PC. Optionally, host section 206 functions as a tabletPC.

Sensor section 202 and/or host section 206 are optionally in operativecommunication with a controller section 204, an exemplary embodiment ofwhich is described in further detail below. Controller section 204optionally provides an interface between sensor section 202 and hostsection 206.

FIG. 3 depicts a schematic 300 depicting data flow between the variouselements of sensor section 202 and controller section 204 and to/fromhost section 206, in accordance with an exemplary embodiment of theinvention.

As an overview of the operation of schematic 300 an object, such asobject 102 or a finger or hand of a user, is placed on sensor array 203.As shown, sensor section 203 comprises a series of activated electrodes302 (a first array of electrodes) and passive electrodes 304 (a secondarray of electrodes). Switching apparatus 306 applies an AC signal,optionally a pulsed AC signal, to at least one of activated electrodes302. Signals in the range from 10 to several 10 s of kHz are consideredto be suitable for the present invention, although higher and lowerfrequencies may be used. A signal is transferred, by capacitivecoupling, to each of passive electrodes 304. It should be understoodthat in some embodiments of the invention, even when no object is placedon the sensor, a signal is transferred to passive electrodes due toparasitic capacitance at the junctions—the “steady state vector”.Passive electrodes 304 are each connected to sensor electronics 310,optionally in the form of an ASIC and optionally comprising a series ofsensor lines 311. Each sensor (pipeline) line 311 optionally includes anamplifier 312 with a high input impedance, a filter 314 which filtersout signals that are not near the frequency of the AC signal, and asample and hold circuit 316 which periodically samples the filteredsignals and transfers them to an Analog to Digital converter 318 toconvert the sampled voltages into digital form. Thus sensor line 311converts AC signals present on a passive electrode with which it isassociated into a digital signal that represents the signal coupled tothat electrode from the particular activated electrode that isactivated. These signals are later analyzed by the controller whichsends further information (characteristics of the signals, such asmagnitude of the received signals, calculated DFT, phase etc.) to thehost computing device which determines the position/orientation/identification etc., as described below.

Electronic circuitry 320 optionally receives the digital values fromA/Ds 318 and processes then for transfer to a host via a connection bussuch as an RS232, RS-422, RS-423 or USB connection, or any data transferbus known in the art. Electronic circuitry 320 also receives commandsfrom the host via connection 330. Digital Fourier Transformation (DFT)is optionally performed on the digitized signal by DSP 324 to calculatethe magnitude and phase of the coupled signal at a specific frequencynamely the frequency of the signal inputted on the activated electrode.

Optionally, DSP 324 receives routing commands (e.g., which activatedelectrodes should be activated and when) and based on these commandsgenerates serial routing commands to switch AC sources (e.g., the outputof amplifier 325 via an analog/digital converter 326) to a desiredactivated electrode or electrodes. CPLD 322 optionally provides samplingcommands to unit 310 to activate the sample and hold circuits and theA/D.

Electronic circuitry which can be in the form of an ASIC or separatecomponents or which can be combined with sensor electronics 310 in asingle ASIC, optionally includes Complex Programmable Logic (CPLD) 322,to convert the signal from electrodes 304 from serial representationinto parallel representation (in short, the CPLD is a ‘Serial toParallel’ converter) which is passed to a Digital Signal Processor 324,such as a TMS320VC5402, which optionally identifies and/or determinesthe position and/or the orientation (or any other relevant information)of an object, for example paddles 108, 110 placed on a surface ofapparatus 100. The methodology used for these tasks is described herein.

In an exemplary embodiment of the invention, electrodes 302 and 304 aresubstantially transparent such that sensor array 203 is transparent. Inan embodiment of the invention, as indicated above, sensor array 203 isoverlaid on a display such as an LCD display. This display can beconfigured to show the game board (or any other background that isappropriate to the task being performed by apparatus 100) as well asvariable information responsive to movement of the objects 102 or tocommands from a host (not shown).

It is noted that the structure of the tablet (except for the absence ofan excitation coil) can be generally the same as that described in US2004/0095333, the disclosure of which is incorporated herein byreference, and that the electronics described in this reference can besimilar to that utilized in the exemplary embodiment of the presentinvention. In an embodiment of the invention, an excitation coil is usedwith apparatus 100 along with electromagnetic objects, which areoptionally excited by the excitation coil. However, it is noted thatthere is no switching of inputs in the device shown in US 2004/0095333and that thus switching apparatus 306 is not present. In addition, whilein US 2004/0095333 the differential amplifiers have inputs fromdifferent electrodes into their two inputs, in the device shown in FIG.3 only one of the inputs of the differential amplifiers is used, beingconnected to a single one of the passive electrodes 304. The other inputis connected to a reference voltage. It is also noted that in someembodiments of the invention, the overall display size is larger thanthat of a tablet. Optionally, a plurality of displays are tiledtogether.

It should be understood that the electronics described above (and in theincorporated references) and the division of tasks between the variouscircuitry and between the circuitry and the host is exemplary only andis not meant to be limiting. Other ways of dividing the tasks and othercircuitry will occur to persons of the art. Thus, it may be moreadvantageous to have more computation performed in the DSP to reduce thedata flow between the computer and the host. It may also be useful forthe scanning to be completely controlled by the electronics shown inFIG. 3, rather than receiving commands from the host. Other changes willoccur to persons of skill in the art.

The inventors have found that a small conductive element (token) such asthose described below, when placed on an electrode crossing causes thecoupled signal to increase by about 10%, apparently by increasing thecapacitive coupling between activated and passive electrodes. Thepresence of a finger, on the other hand, decreases the coupled signal by20-30%. As described in more detail below, with respect to FIGS. 7A and7B, this difference is measured and processed to produce an indicationof the presence of a token or finger at the electrode crossing, inaccordance with an embodiment of the invention.

In some embodiments of the invention, the activated electrodes areactivated serially, for example by switching a signal from an amplifier325 into particular lines based on a serial routing command whichcontrols the switches in apparatus 306, as described above.

In order to speed up report rate, such as shown in FIG. 15, the activeelectrodes 302 are divided into a number of groups 1502, 1504, 1506wherein the active electrodes (such as 1510, 1512) in each group areactivated sequentially but the groups work simultaneously. This can beaccomplished only by using a handful of non-mutually interfering(orthogonal) frequencies which are used to activate electrodes 302. Forexample, at a sampling rate of 200 kHz, exemplary frequencies of 20 kHz,30 kHz, and 40 kHz are used. In some embodiments of the invention, thishandful of frequencies are assigned one to each group. It should beunderstood, however, that these frequencies change depending on thesampling rate, and that they are not limited to 3 frequencies, as 20kHz, 30 kHz and 40 kHz are by way of example only.

Alternatively, a source is connected to each of the activated electrodes302 and each source supplies a signal at a different frequency todifferent electrodes. With somewhat more complex sensor electronics itwould then be possible to determine the position much faster without anysignal scanning. Furthermore, the system could be made much moresensitive to movements of objects, since software algorithms running onDSP 324 could compare signals before and after movement. Referring toFIG. 4, an application-specific integrated circuit (“ASIC”) 400schematic (corresponding generally to sensor electronics 310 of FIG. 3)is shown. Essentially, an ASIC is a microchip designed for a particularapplication. Each passive electrode 304 is optionally connected to aninput of a differential amplifier 402. The other input of thedifferential amplifier is optionally connected to a DC referencevoltage, to avoid signals on neighboring or remote lines generated bythe same or other tokens canceling each other. The differential sensorsignal is amplified and forwarded to a switch 404, in accordance with anexemplary embodiment of the invention. Optionally, switch 404 selectsone or more (a sub set) of a plurality of inputs to be processedfurther.

In an exemplary example where only a single element is in use (such as astylus of pointer) then only inputs corresponding to inputs near theprevious position of the element are sampled. In applications wheremultiple objects are in use, and where objects are placed on and removedfrom the surface, then the entire surface is scanned.

In an exemplary embodiment of the invention, the selected signal isamplified and/or filtered by the filter and amplifier 406. The resultantsignal is then sampled by an analog to digital converter 408, inaccordance with an exemplary embodiment of the invention. The signal isthen sent to CPLD/DSP 322/324 located in electronics 320 (FIG. 3),optionally via a serial buffer 410, in an exemplary embodiment of theinvention.

In some exemplary embodiments of the invention, each ASIC 300 containstwo identical channels. Optionally, each ASIC 300 channel is comprisedof four (4) differential inputs to allow sampling as close as possibleto the passive electrodes. It should be noted that while theseelectrodes (as well as the activated electrodes) ideally should have alow impedance to reduce noise and pick-up in an actual situation, theelectrodes may have relatively high impedance such as several hundredthousand ohms or more. This may be desirable in order to increase thetransparency of array 203. However, under other circumstances, in whicha lower impedance is possible, a single ASIC which handles all of thepassive electrodes may be used. Alternatively, separate amplifiers,filters and A/D may be provided for each line.

In some exemplary embodiments of the invention, ASIC 300 is providedwith a shutdown capability, which switches ASIC 300 off. Optionally,CPLD/DSP 322/324 shuts down ASIC 300 or puts it into a hibernate modewhenever it is not needed, in order to reduce energy consumption. Insome embodiments of the invention, ASIC 300 is periodically and/ortemporarily activated by CPLD/DSP 322/324 to sample sensor array 203 foractivity FIG. 5 shows a pre-determined configuration of tokens 502, 504,508 and 510 located on the bottom of an object 500, in accordance withan exemplary embodiment of the invention. Patterns or configuration suchas these and those shown in FIGS. 6A-F, 10-12, and 16A-D can be used toidentify an object information code and/or determine the orientation ofthe object containing the tokens.

It should be noted that in the object shown in FIG. 5, the tokens arenot necessarily all the same in all embodiments. For example, at leastone token 502 has a modified capacitance (described below) pattern. Ingeneral, the configuration of tokens is placed at or generally beneath adetection surface of an object. In an exemplary embodiment of theinvention, some tokens, such as tokens 504, 508 and 510 of FIG. 5, are100% coated with a conductive material, such as copper.

In principle, it is believed that a token with more area covered byconductive material will create greater capacitance on the junctiontouched by the detection surface of the object, thus its coupling effectwill be greater than a token with less conductivity. However, in otherexemplary embodiments of the invention, tokens have a smaller percentageof coverage of conducting material, modifying their capacitive coupling.The token patterns themselves are optionally variable. Different levelsof conductivity (and hence of capacitive coupling) can be achieved byusing different conductive materials. Optionally, the distance from theconductive material to the sensor array 203 is adjustable for differenttokens by placing a dielectric layer between the conductive material andthe outer surface of the object. This variation results in variedamounts of capacitive coupling as well. In some exemplary embodiments ofthe invention, the diameter of a token is equal to twice the distancebetween two close edges of consecutive electrodes plus the width of anelectrode. Optionally, the diameter is larger or smaller than the above,depending on the needs of the application. Using a token at least thislarge assures that the token covers a plurality of junctions, whichmakes determination of the center of the token more accurate.

In some embodiments of the invention, the conductive signature of anobject is selectively changeable, for example to change its objectinformation code (identity). FIG. 6A shows a physical object 600provided with a pattern of tokens 602, 604, 606 on the bottom of object600. It can be seen in this embodiment that the pattern has a generallytriangular “footprint” or form and that tokens 604 and 606 are eachselectively connected to token 602 by a connection switch. In anembodiment of the invention, connection switch material is conductive sothat when the switch is closed, a connection is made between the tokenson either side of the switch changing the pattern configuration andwhich in turn alters the sensor array 203 detectable signature. In anembodiment of the invention, the diameter of each token is smaller thanthe distance between two electrodes on sensor array 203. It should beunderstood that the arrangement shown in FIG. 6A is by way of exampleonly, and does not indicate any required scale or shape. Furthermore, inthe embodiments depicted in FIGS. 6A and 6D, the conductive signature ofthe objects is changed by flipping a switch, it should be understoodthat some objects are provided with the ability to physically changedimensions, causing at least one token 652 to physically move 656 inrelation to at least one other token 654 of the pattern, andsubsequently changing the identity of the object 650, as shown in FIG.6E.

FIG. 6B shows a footprint of object 600 positioned on sensor array 203where the switches are turned off, in accordance with an exemplaryembodiment of the invention. In an embodiment of the invention, a signalis applied to activate an electrode 608. A signal is transferred, bycapacitive coupling due to the presence of tokens 602 and 604 at twojunctions on electrode 608, to passive electrodes 614 and 616. In asimilar manner, when a signal is applied to activate electrode 610, asignal is detected on a passive electrode 612. Optionally, electrodes608, 610 (or groups of electrodes, as described above) are activatedseriatim.

Referring to FIG. 6C, footprint of object 600 is shown positioned onsensor array 203 where the switches are turned on, in accordance with anexemplary embodiment of the invention. In an embodiment of theinvention, turning the switches on creates a conductive connectionbetween tokens 602, 604 and 606. As a signal is applied to activateelectrode 608, a signal is transferred, by capacitive coupling due tothe presence of tokens 602 and 604 at the junctions, to passiveelectrodes 614 and 616, enabling an output signal to be detected atthose electrodes. Since tokens 602 and 606 are in conductiveconnectivity, the signal is also transferred to token 606. In anembodiment of the invention, this enables a signal to pass to passiveelectrode 612, which is also detected. Correspondingly, when a signal isapplied to activate electrode 610, an output signal is detected onpassive electrodes 612, 614, and 616 since all three tokens are inconductive connection. In a sense then, the identification of object 600has been changed by turning the switched from off to on, since theapplication of signals to the input of sensor array 203 produces twodifferent outputs based on the on/off configurations. In someembodiments of the invention, two switches are used for an object,instead of one in order to avoid ambiguity. An ambiguity can arise in asituation where only one switch is used and the two tokens which areconnected by the switch are placed on the same passive electrode,preventing the system from differentiating between the on and offconfigurations.

In an exemplary embodiment of the invention, token of different sizesare used instead of two switches in order to resolve the above describedambiguity. Such an embodiment is shown in FIG. 6D, wherein an enlargedtoken 632 is provided to an object 630. The operation of object 630 withrespect to sensor array 203 is substantially similar to the operationdescribed with respect to object 600, however it should be understoodthat the enlarged nature of token 632 exhibits a different capacitivesignature on sensor array 203 than token 602 or the other two tokens634, 636 on object 630. For example, in an embodiment of the invention,enlarged token 632 is sized to touch at least one more electrode thanthe other tokens.

The different on and off configurations of the switch, which can bereferred as the different conductive states of the object can be deducedfrom the signals detected at the passive electrodes, as shown in FIGS.6B-C. In an embodiment of the invention, when the object is a gamepiece, the different conductive states of the object can indicatedifferent ‘modes’ of the game piece. For example, different players (onemode can represent a king and the other queen), different status (a“dead” or “living” player), different colors of player, and the like.Optionally, the conductive state change can invoke an action that theobject performs, for example shooting, hitting, etc. In some embodimentsof the invention, the tokens are sized so that the diameter of thetokens assures that the token covers at least one junction. Optionally,each token covers more than one junction. It should be understood thatthe shape, size, conductive material, and/or geometric pattern createdby the tokens is variable to indicate a variety of identities to theobject on which the tokens are located.

It should be noted that while an object's position and to some extentits identification can be determined by locating one token thereon, aplurality of tokens are optionally used, as shown in the exampledepicted in FIG. 5, for example to increase the number of possibleseparately identifiable objects and/or to allow for optionaldetermination of orientation of the object. An object is optionallyrepresented (and identified) by a unique combination and number oftokens and optionally, the varied conductivity of (or capacitivecoupling induced by) one or more of them. This enables discernmentbetween specific objects and also allows for determination oforientation as well as location.

For example the position of the object 500 in FIG. 5 can be defined asthe intersection of connecting lines drawn across the diagonals betweenthe centers of the tokens located at the corners of the object. Itsorientation can optionally be determined according to the differentcapacitive coupling of the token located thereon and this can bedetermined upon conducting an analysis of a delta value of the tokenslocated on the object. The delta value of a token or finger is adifference (amplitude and phase) between a signal detected on therespective passive line in the presence of the token or finger and asteady state signal present when no token is present.

A number of exemplary methods are provided for using the apparatus 100described above. In some exemplary embodiments of the invention, methodsare used to calculate whether a finger or an object is located onapparatus 100. In some exemplary embodiments of the invention, methodsare used to determine the center of a token. In some exemplaryembodiments of the invention, methods are used to identify position,identification and/or orientation of an object located on apparatus 100.The area and magnitude of capacitive coupling can also be used toperform different functions such as ‘scroll up’, ‘scroll down’, and/or‘cursor’ etc. Referring to FIG. 7A, a method for differentiating betweenobject and/or finger contact and/or finger hovering is shown, inaccordance with an exemplary embodiment of the invention. As describedwith respect to FIG. 3, when a conductive material, such as a token, isat a junction between an active electrode (y-axis) and a passiveelectrode (x-axis), then the voltage on the passive electrode will belarger than a voltage on it when there is no token at the junction. Thisstronger signal means a greater signal magnitude which is calculatedusing a discrete Fourier Transform (“DFT”), or other means such as anFFT, in accordance with an exemplary embodiment of the invention. A DFTor FFT is used since it conveniently acts to not only provide theamplitude and phase of the signal, but also to differentiate the signalfrom noise or signals at other frequencies. When the activatedelectrodes are activated by signals of different frequencies, then theFFT or DFT is a convenient way of determining all of the delta valuesfor lines crossing the passive line being sampled.

As shown in FIG. 7B, a human finger 710 causes the opposite effect(i.e., signal reduction) of a conductive token 712, possibly because ahuman is can be modeled as a grounded added capacitance when touchingthe sensor array, whereas a token can be modeled as a floating addedcapacitance. This enables the system to easily differentiate between atoken and a finger, in an embodiment of the invention. In addition, thestrength of the signal for a finger allows differentiation between afinger touching the surface and one hovering above the surface, sinceboth touching and hovering produce signals that are large enough to bereliably detected.

Method 700 for discerning between conductive object and/or fingercontact commences with learning (702) a steady state vector andoptionally various delta vectors between the various inputs and outputsof sensor array 203. In general, with no tokens or other elements onsensor array 203, the activated electrodes 302 are energized seriatim,and a steady state vector for a particular electrode 302 is calculated.The steady state vector comprises, as its elements, a steady state value(amplitude and phase) of the voltages induced for each of the passiveelectrodes, when the activated electrodes 302 are energized and noobject is placed on or over the sensor. Optionally, othercharacteristics of the detected signal are used to calculate the steadystate value. This process is generally performed in the factory,although it could also be performed regularly in the field.

Optionally, in a sensor array 203 where the behavior of junctions ishomogenous, learning the steady state vector of only one junction mightbe needed. However, in some exemplary embodiments of the invention, eachjunction is measured because of the heterogeneous behavior of thejunctions caused by different gains of amplifiers, different capacitancebetween transmitters and receivers, and other effects. The matrixcontaining the steady state values is optionally stored for comparisonwith measured signals.

Characteristic delta values are determined for various tokens ofdifferent “strengths.” In general, a conducting line parallel to theactivated electrodes is placed over a column of junctions. The outputsof the passive electrodes are then subtracted from the steady statevector for that activated electrode to provide a characteristic deltavector of that particular conductor. Optionally, this conducting line isthen moved to the next activated electrode to produce the next deltavector of that particular conductor and that particular electrode 302.

Delta vectors may also be determined for various capacitive couplinglevels, to improve the ability of the system to discern differencesbetween them. Since different capacitive tokens cause different amountsof coupling, they can be differentiated by providing multiple thresholdsfor the coupled delta signals to allow for identification of thecapacitive coupling. It is not believed necessary to provide an array ofdifferent characteristic delta values for fingers; a singlecharacteristic delta value is believed to be sufficient. In someembodiments of the invention, a second threshold is established fordetecting a body part which is hovering over sensor array 203, but notactually touching it.

At least one object and/or finger is placed on the sensor array 203while apparatus 100 is in use for determining object information, in anexemplary embodiment of the invention. A delta value is calculated (704)for each junction in order to discern between object and/or fingercontact or hovering. In an exemplary embodiment of the invention,scanning to determine the presence of an object and/or a finger locatedon or near (hover) sensor array 203 is performed in the same methoddescribed during the learning (702). In an exemplary embodiment of theinvention, delta current DFT results are generated based on the measuredsignal from each junction respectively and a delta vector is calculatedby subtracting the steady state DFT results from the current delta DFTresults. Optionally, the delta vectors are stored and compared with thecharacteristic delta values determined in the learning phase to identifywhat is causing the coupling.

In an exemplary embodiment of the invention, noise reduction orelimination is performed (706) on signals generated during the pollingof the junctions, as described above, during actual operation (see 708).Optionally, noise reduction or elimination is also performed duringlearning (702). Optionally, noise is reduced (in addition to the filtersshown in FIGS. 3 and 4) by routing a signal to the transmitters which isof a pre-determined, specific frequency and performing DFT at saidspecific frequency on the sampled signal thereby eliminating noisesignals at irrelevant frequencies. Optionally, noise reduction isperformed (706) by determining the phase of a vector. For example,despite their great influence on the magnitude of the steady statesignal, the influence of both fingers and conductive materials on itsphase is minor. Thus if a conductive material touches a junction itscorresponding delta vector phase in the delta matrix will be close tothe steady state vector phase. However, if a finger touches a junctionits corresponding delta vector phase in the delta matrix will be closeto 180 degrees from the steady state vector phase, since 180 degreesrepresents a decrease in the magnitude of the signal. Noise reductioncan optionally be performed by eliminating any measured delta value witha phase outside of those two approximately known phase regions i.e. anydelta value with a phase not close to 180 degrees from the steady statevector phase or not close to the steady state vector phase, for example±10 degrees or ±20 degrees. Optionally, noise reduction is performed(706) by increasing the time the activated electrodes 302 are energized,which improves SNR (Signal to Noise Ratio). Optionally, the passiveelectrode 304 is sampled several times and an average value of themeasurement is calculated.

During actual operation of the system, recognition (708) of a fingerand/or a conductive object, such as a token, is performed by analyzingdelta values, in accordance with an exemplary embodiment of theinvention. According to an exemplary embodiment of the invention, ajunction can be determined to have been touched by a finger if itscorresponding delta value (optionally after noise reduction) has amagnitude over a certain threshold and its phase is approximately 180degrees from the previously measured steady state value. If its phase isapproximately 180 degrees and its value is below that threshold butabove a second threshold, then the situation is identified as hovering.In contrast, a conductive object (token) provides a different measuredeffect, and thus a junction can be classified as having been touched bya conductive object if the delta value has a magnitude sufficiently overthat of the steady state and its phase that is similar to the steadystate phase. The different tokens can be identified by utilizing a deltamatrix defined for different “strengths” as described above.

An exemplary approximation method for finding the center of a token isnow described, in accordance with an exemplary embodiment of theinvention. In an exemplary embodiment of the invention, the closer thecenter of a token is to a junction, the greater the measured deltavector of the junction will be. By using this knowledge, measurement ofdelta vectors of various junctions allows for an approximation of thetoken's center location.

Measurements are made when an activated electrode is actually energizedand a delta vector is calculated according to methods described herein.This delta value contains the deltas of the responses of all of thepassive electrodes to this energizing. In general a map of the deltavalues (a matrix of values defining the coupling between each input andeach output) is determined.

A determination is made of which junctions contain a token. Delta valuesfor neighboring junctions are compared, to determine which measuredjunction has the higher delta value. This higher value is used todetermine the center of the token. The junction with the higher deltavector sets the x and y coordinates of the center of the token.Optionally, an error correction is made to correct for the fact that thetoken may not be directly on the junction. By adding or subtracting d/4from these (x,y) coordinates at each axis, depending on which is thedirection of the crossing with the next higher delta value, the maximumpossible error is reduced. This is not a strict requirement. “d” is thedistance between electrodes' center, which can vary depending on theresolution required in a particular embodiment. In an exemplaryembodiment the spacing is 4 mm from center to center. In an exemplaryembodiment the width of each electrode is 1 mm.

In an exemplary embodiment of the invention, errors in the calculationof each coordinate are bounded by d/4 and the total calculation error isbounded by d/√8.

A weighting method for finding the center of a token, in accordance withan exemplary embodiment of the invention, is now described. Instead ofidentifying the closest junction to the token's center, choosing thatjunction as the center and then correcting slightly for error, thismethod uses a measurement of more than one junction in order todetermine the center of a token, in an exemplary embodiment of theinvention. The junctions are measured for their delta values (as in thepreviously described method) in order to determine a starting point forpinpointing the location of the center of the token, in some exemplaryembodiments of the invention. This will generally result in a deltamatrix of values. A junction identified as having the highest deltavalues as compared to surrounding junctions is chosen to be thereference location (x,y) in the formulas below. The delta value of atleast one neighboring junction, generally the junction with the nexthighest delta value, in each direction is utilized to determine thecoordinates of the center of the token.

In general, the two highest delta values in each axis are used and thecenter is computed to be the junction with the higher value corrected bymovement to the junction with the next higher value equal to thedistance between the junctions multiplied by the ratio between the deltavalues. Optionally, the ratio is a function of the delta values at thejunctions. Optionally, the ratio is calculated by dividing the deltavalue of the next higher value and the sum of the delta values.Alternatively, more complex schemes can be used utilizing more neighborsand/or different formulas.

Referring to FIG. 8, an exemplary look-up table method 800 for findingthe center of a token is shown, in accordance with an alternativeexemplary embodiment of the invention. In some exemplary embodiments ofthe invention, the center of a token can be determined by measuring andconsidering (802) the delta values of junctions in proximity to thetoken. In some exemplary embodiments of the invention, four (4)junctions are measured. Optionally, two (2) junctions are measured.Optionally, more or fewer junctions are measured depending on theaccuracy requirement for finding the center of the token. Oncemeasurements of delta vectors are determined, conferring (804) with alook-up table provided with previously determined delta vectormeasurements should provide an approximate location of the center of thetoken. Optionally, the look-up table is comprised of experimentallyderived results. Optionally, the look-up table is comprised ofmathematically modeled results. It should be noted, that the more valuesthat are located in the look-up table, the higher likelihood of accuratelocation of the center of the token. Once values in the look-up tablecan be correlated to the measured delta vectors (for example, using amean square error method), the x and y coordinates of the center are set(806).

In some exemplary embodiments of the invention, the center of a tokencan be determined by a combination of the described methods. Optionally,an averaging of several results obtained from the different methodsdescribed is used in order to calculate the center of token.

FIG. 9 depicts an exemplary geometric method 900 for finding theidentification, orientation and/or position of an object, in accordancewith an exemplary embodiment of the invention. By using a geometricpattern created by an array of tokens located on an object, apparatus100 optionally determines identification, orientation and/or positioninformation of the object. A plurality of junctions of a sensor array203 are measured (902) in order to determine if a pre-defined geometricpattern of tokens exists and if so, which geometric pattern. Once atleast one token is detected by sensor array, using apparatuses andmethods such as described herein, the center of each token is optionallycalculated (904) in order calculate the identification and positioningof the object of which the token is a part. An analysis of a pluralityof tokens allows for the determination (906) of size and/or shape of thepattern of the tokens, for example defined by a line or lines connectingthe centers of the tokens, and/or any other shape attributes(perimeter/area/contour) of the object with which the tokens areassociated. Comparison (908) of the determined size or other attributesto a look-up table comprised of size and other identificationassociations permits the identification of a particular object.

Before going on to the next act (910), it will be useful to discussseveral exemplary token patterns which allow for both identification andorientation determination. FIGS. 10 and 11 describe two differentexemplary geometric structures of token patterns usable in embodimentsof the present invention.

FIG. 10 shows a pattern 1000 of tokens 1002 on the bottom of an objectwhich pattern has a triangular form. In this embodiment the differentobjects are distinguished by the distances between the tokens beingdistinguishable, i.e., the distances used in two different objectshaving a measurement accuracy which is better than the difference in thedistances. In order to avoid size misidentification the allowed distancebetween centers for different patterns must be greater than four timesthe error of the method used for finding the center of a token. In orderto assure that direction determination is unambiguous equilateraltriangles are optionally not used. Optionally, an isosceles triangle isused. Optionally, the system is capable of distinguishing betweenseveral lengths, in accordance to the different possible combinations,several isosceles triangles are used. For example, if 3 differentlengths are used, there are 6 different combinations for isoscelestriangles. Additionally, optionally or alternatively, the objectinformation code can be determined based on a pattern of differentcapacitive couplings in the tokens. In addition, different sizes oftokens can be used. Optionally, different conductivity density can beused in each token.

FIG. 11 shows a pattern 1100 of tokens 1002 in the form of a V. In thisembodiment, most of the identifiable objects will not have one or moretokens shown in the pattern. In an embodiment of the invention, token1004 is present and has a distinctive coupling value or size. At leastone of the tokens should be present in each of the sides of the arrow,so that direction can be determined unambiguously, in some embodimentsof the invention. Once the positions of the tokens that are present aredetermined, a template matching algorithm is optionally used todetermine which the object information code of the object beingidentified and what its direction is. While an object with seven tokensis shown, a greater or lesser number can be used, depending on thenumber of identifiers required. In addition to possibly having one ormore missing token in the pattern, some of the tokens may have adifferent capacitive coupling value. Optionally, some of the tokens 1002may have different size. Optionally, the distance between the tokens1102 varies between different objects.

In an embodiment of the invention, an object information code of anobject is detected by recognizing distances between tokens. FIG. 16Ashows a pattern 1600 of tokens 1602, 1604, 1606 and 1608 which arepositioned proximal to sensor array 203, in an embodiment of theinvention, when the object is placed on sensor array 203. Using thedetection methods described herein, the object information code of theobject can be determined by measuring the detected distance between thetokens, for example dl between token 1602 and token 1604, d2 betweentoken 1604 and token 1606, and d3 between token 1606 and token 1608. Theanalysis which results in the measurement of d1, d2, and d3, which aremeasured from the center of token to the center of token, enables theidentification of the object which is known to have this d1, d2, d3configuration. In order to increase the number of possible identities,the number of rows and/or columns of tokens can be increased, the tokensthemselves can be of varying size, the conductivity of the tokens can bevaried, and/or the distances between the tokens can be varied, asexamples. FIG. 16B shows a pattern 1610 which consists of two rows and 4columns of tokens, with up to 7 possible distances between the varioustokens (more if the rows are not consistently parallel to each other).In some embodiments of the invention, a predetermined number ofpredefined distances are used for identifiers. Taking pattern 1600 ofFIG. 16A as an example, there are 4 tokens and 3 distances (d1, d2, andd3). If there are 5 options for distances and the size of the tokens isfixed, there are 5^3 total possible identities for the object.

In an embodiment of the invention, a binary pattern is used to identifyan object. The binary pattern is implemented, in an embodiment of theinvention, by predefining a distance, d, between token slots and eitherplacing a token in the slot, indicating “1”, or leaving the slot empty,indicating “0”. Optionally, a different capacitance and/or token size isused to indicate “1” or “0”. In some embodiments of the invention,bracket slots 1652 are used to signal a start and end of the binarypattern. FIG. 16C shows binary pattern 1650 in which the bracket slots1650 are filled but no tokens are located in each of the other slots,indicating a “0 0 0 ” pattern. FIG. 16D shows two other identitypatterns 1660 and 1670, which exhibit the identities “0 0 1” and “0 1 1” respectively. In some embodiments of the invention, the number ofslots in a row are increased or decreased (i.e. the number of columns isincreased). Optionally, the number of rows is increased. In someembodiments of the invention, the distance, d, between the tokens islarge enough that individual slots can be detected but is small enoughto enable the pattern to be used with a game board sized object.

One problem that may arise is the determination of which tokens belongto which objects, since it is possible that the positioning of theobjects is such that tokens of adjacent objects form triangles or arrowsthat could themselves signify objects.

FIG. 12 shows such a possible configuration in which two objects areclose enough so that there is ambiguity as to which objects are present(i.e. what object information code would be detected). Two objects 1210and 1220 are present each with 3 tokens. It is noted that the patternsof tokens on the objects themselves are different so that if theassociation of tokens with objects is made, then there would be noproblem in identifying the objects themselves.

It is noted that object 1210 has three tokens 1212, 1214 and 1216, whileobject 1220 has three tokens 1222, 1224 and 1226. However, tokens 1216,1224 and 1226 form a triangle that meets the requirements describedabove.

To solve this potential problem, the grouping of tokens as part ofobjects follows the following procedure:

(a) Find all the token's centers.

(b) Pick one of the tokens and check if it can be a part of more thanone valid triangle (for example, if only isosceles triangles aresupported, a triangle that is not isosceles is invalid. In addition, thetriangle sides should be equal to one of a possible set of permittedlengths).

(c) Select a token that is a part of ONE valid triangle ‘mark’ all thetokens participating in said triangle as ‘used’.

Optionally, the patterns of the objects are determined such that such atoken exist. Optionally, the sizes of the triangles are determined in away that assures that such a token exist.

(d) Repeat (b) and (c) for all the ‘not used’ tokens—establish all thevalid triangles. Each triangle corresponds to a single object.

In order to assure that two tokens do not affect a single junction,sufficient margin should be a minimal distance between every two tokens,either on the same object or in different objects.

Returning to FIG. 9, in some exemplary embodiments of the invention,orientation information is determined by apparatus 100 using a geometricmethod. Naturally, certain shapes are not entirely equilateral. Use ofshapes which have at least one side not the same as the others allowsfor a determination of orientation (910), in an exemplary embodiment ofthe invention. For example, three tokens can be located on a triangleshaped object, wherein one side of the triangle is a different lengththan the other two sides, which are equally sized. An analysis of theposition information of the tokens reveals the base of the isoscelestriangle-shaped object. Orientation is optionally indexed according tothe base in some convenient and/or useful manner. Optionally, theorientation of the object corresponds to a line orthogonal to the baseof the triangle. In some embodiments of the invention, the geometriccenter of the object is considered its position on sensor array 203.

For the pattern of FIG. 11, the orientation of the object is easilydetermined from the direction of the arrow formed by the tokens that arepresent (and those that are missing). In making this determination it ishelpful if the token at the point of the arrow has distinguishablecharacteristics (such as coupling value, size).

Referring to FIG. 13, an exemplary varied conductivity and/or sizemethod 1300 for finding the identification, orientation and/or positionof an object is depicted, in accordance with an exemplary embodiment ofthe invention. A delta value is measured (1302) for a plurality oftokens. Based on the measurement, specific tokens are optionallyidentified (1304) by the measured delta vector value. An analysis of aplurality of tokens identified thusly allows for their association(1306) to a specific configuration of tokens and hence a specific objectcan be associated (1308) with that pattern. In some exemplaryembodiments of the invention, at least one token located on an objecthas a varied conductivity and/or size. As described in relation to FIG.5, a varied conductivity token 502 is optionally incorporated into arecognizable multi-token configuration, such as shown in FIGS. 5, 6A-F,10-12, and 16A-D. In some exemplary embodiments of the invention, thetokens of a recognized configuration are positioned at known locationson the object. Optionally, all objects identified utilizing this methodare the same shape and size. Optionally as few as two tokens are used toprovide information about an object. Optionally, more than two tokensare used to provide information about an object. Optionally, more thanone varied conductivity token is used. Optionally, more than one sizevariable token is used. Optionally, each varied conductivity token isvaried in conductivity from the others.

Orientation information of an object is also optionally determined(1310) using the varied conductivity and/or size method 1300. Forexample, a known orientation of the object is optionally associated withthe tokens' configuration which incorporated at least one token whichvaries in its conductivity and/or size. Upon the analysis of the tokenconfiguration, including the identification of a varied conductivityand/or size token, the object's orientation can be known.

In accordance with some exemplary embodiments of the invention, theboard can also be used as a tablet of a PC.

In one exemplary embodiment of the invention, the tablet has twoconfigurations. In one of these configurations the tablet has theconfiguration and operation as described above and is used to find theposition of objects, such as game pieces and/or fingers and optionallythe orientation of the game pieces. In the other it reconfigured to havethe configuration shown in US 2004/0095333 and it then functions as atransparent stylus sensitive display using electromagnetic stylusdetection rather than capacitive coupling.

An exemplary method of providing such a changeover is illustrated inFIG. 14, which shows a layout and sample electronics for a sensor array1400. In this embodiment a change over must be made from theconfiguration disclosed above in which a signal is inserted in one setof electrodes and detected in the other set and a system in which thesignal is generated in both sets of electrodes by an electromagneticwave as in US 2004/0095333. In the following system, no switches arerequired (except for switches required to activate one or anotherelectrode, e.g. apparatus 306 of FIG. 3). If switches can beaccommodated, then the number of amplifiers can be significantlyreduced.

A characteristic of the embodiment disclosed is that there areamplifiers on more than one end of the passive electrodes. Considerfirst the two ends of the activated electrodes 304. On one end,indicated as 1402, each of the electrodes is also connected to apparatus306 so that the activating signal is routed to the activated electrodewhich is to be energized. On the other end, indicated as 1404, adifferential amplifier is connected to two lines as in US 2004/0095333.While connection of adjacent electrodes is shown, the variants shown inUS 2004/0095333 are also possible. Alternatively to the connections fromswitching apparatus 306 being connected at end 1402 they can beconnected at end 1404.

One end of passive electrode 304, designated 1406 has one input of adifferential amplifier connected to each electrode. The unconnectedinput is connected to a bias voltage. This amplifier is used todetermine the capacitive coupling as described above.

The other end of passive electrodes 304 designated 1408 has aconfiguration that is the same as that of end 1404 of the activatedelectrodes.

Optionally, the change over can be achieved by software solutions, bysubtracting the detected signals at a pair of electrodes to obtain adifferential signal, similar to the output of the differentialamplifier. In addition, the stylus can be detected in a single endedconfiguration and not necessarily in a differential configuration.

In a second embodiment of the invention, a stylus is supplied with aconductive tip. In use, there is no need to reconfigure the tablet orelectronics when it is desired for the device to operate as a stylussensitive tablet, since the tip will cause a change in signal in thesame way as does a token. This greatly simplifies the device. Inaddition, it is possible to provide a first type of stylus with arelatively small conductive tip for pointing or writing and a secondstylus with a larger tip for erasing. Since the larger tip will be seenby a greater number of junctions and the coupling will be greater, theidentification of which stylus is used can be easily determined.Alternatively, a single stylus could have two tips; one on either end ofthe stylus. One end has a narrow tip and the other has a larger tip(like a pencil with an eraser). Alternatively or additionally, theconductive tip can be provided in two parts, a first smaller part thatis always at the tip and a second part surrounding the first part thatis lowered to the tip when a button on the stylus is clicked. Thischange can also indicate “right clicking” of the stylus.

In another embodiment of the invention, the object is a mouse, where aconductive pattern is placed on its bottom surface. The mouse is for useover the display screen and can be used as a cursor. In addition, it ispossible to provide a ‘right click’ button and ‘left click’ button, whenpressing each one of these buttons a conductive token is lowered to thebottom surface of the mouse, which can be detected by the system, andindicates a ‘right click’ or ‘left click’ accordingly.

In some embodiments of the invention, the objects are hand held objects.In other embodiments the objects move autonomously on the surface andmay be controlled by a controller via a wired or wireless connection.For example, the objects could be in the shape of a car and bemotorized.

In some embodiments of the invention, movement of the objects iscontrolled by a robotic device controlled by a host or remotely via theinternet.

In some embodiments of the invention the objects may have multipledetection surfaces, as for example a gaming die which generally has sixsides marked with either 1-6 dots or numbers 1-6. In an embodiment ofthe invention, a material on each of the multiple detection surfaces,for example the dots, is conductive such that the conductive materialacts as similar to an identification token. This enables the sensorarray to determine the uppermost number by “reading” the number of dotsfacing the sensor array. It should be understood however, that aconventional gaming die is by way of example only and thatidentification of the multiple detection surfaces does not have tocorrespond to how sides of gaming dice are detected traditionally (i.e.with 1-6 dots on each side detected by the eye). Optionally, a token isnot used per dot, for example where a distinctive conductive pattern isused on at least one of the multiple detection surfaces whichcorresponds to a number of dots and is detectable by the sensor array.

In another embodiment, the object is a game piece which can be reversedand has a different meaning depending on which side is up. For example,one side could represent a king in checkers or could identify theplayer, when the object is inverted, the other player is identified withthe game piece.

Other multi-sided objects and their uses will occur to persons of skillin the art.

In an embodiment of the invention, finger and/or object touches are usedto identify a person for security purposes. For example, a person couldbe issued a “key” which is comprised of at least one object having atleast one token located thereon. Using the methods and apparatusesdescribed herein, the key is placed on a sensor array, possibly at apredefined specific location on the array, and information about the keyand optionally its location is determined, for example is the key validand/or in the predefined valid location on the array. Optionally, fingertouching, or even the contour of a larger body part, is detected inorder to determine information about the finger or larger body part.Similarly to the key embodiment described above, this information isused to permit or deny security clearance to the person. In someembodiments of the invention, both an object such as a key and bodyparts are used in combination to validate the person. In someembodiments of the invention, a gesture made by a body part of a personis detected and identified for validation purposes.

It is to be understood that while the present discussion has centered onhardware and methods of operating the hardware, the present inventioncan be embodied in circuitry, hardware, software, computer readablemedia, and/or programmed computers that are configured and arranged tocarry out the invention.

The present invention has been described using non-limiting detaileddescriptions of embodiments thereof that are provided by way of exampleand are not intended to limit the scope of the invention. It should beunderstood that features and/or steps described with respect to oneembodiment may be used with other embodiments and that not allembodiments of the invention have all of the features and/or steps shownin a particular figure or described with respect to one of theembodiments. Variations of embodiments described will occur to personsof the art. Furthermore, the terms “comprise,” “include,” “have” andtheir conjugates, shall mean, when used in the disclosure and/or claims,“including but not necessarily limited to.”

It should be noted that in the claims the term “control system” is usedto denote a system for controlling the operation of the sensor array andmay include a host computer.

It is noted that some of the above described embodiments may describethe best mode contemplated by the inventors and therefore may includestructure, acts or details of structures and acts that may not beessential to the invention and which are described as examples.Structure and acts described herein are replaceable by equivalents,which perform the same function, even if the structure or acts aredifferent, as known in the art. Therefore, the scope of the invention islimited only by the elements and limitations as used in the claims.

1. A method for detecting an object on a sensor sensitive to capacitivecoupling, the method comprising: simultaneously transmitting signals onat least two electrodes of the sensor, wherein at least one of thesignals transmitted on each of the at least two electrodes has afrequency that is different from a frequency of at least one othersignal transmitted on another electrode of the at least two electrodes;sampling a signal on at least one other electrode crossing the at leasttwo electrodes, wherein the signal is responsive to capacitive couplingformed between the at least two electrodes and the at least one othercrossing electrode; and detecting at least one object from the sampledsignals.
 2. The method according to claim 1, wherein the differentfrequencies are orthogonal to each other.
 3. The method according toclaim 1, wherein the sensor includes a first and a second array ofelectrodes forming a grid with a plurality of junctions between thefirst and second array of electrodes.
 4. The method according to claim3, wherein the first array includes active electrodes and the secondarray includes passive electrodes.
 5. The method according to claim 4,wherein the at least two electrodes are active electrodes and the atleast one other electrode is a passive electrode.
 6. The methodaccording to claim 5 comprising simultaneously sampling passiveelectrodes in response to transmitting a signal on the at least twoelectrodes.
 7. The method according to claim 3, wherein the electrodesof the first array are divided into a plurality of groups, and whereinsignals are transmitted to electrodes in each group serially.
 8. Themethod according to claim 7, wherein the signals transmitted seriallyare of a same frequency.
 9. The method according to claim 7, comprisingsimultaneously transmitting signals to electrodes from different groups,wherein each of the signals transmitted has a frequency that isdifferent from a frequency of the signals transmitted on electrodes fromanother group of the different groups.
 10. The method according to claim1, wherein the electrodes are conductive lines.
 11. The method accordingto claim 1, wherein the at least one object is a body part or acapacitive object.
 12. The method according to claim 11, wherein thebody part is a finger.
 13. The method according to claim 1, wherein thesensor detects multi-touch.
 14. The method according to claim 1, whereinthe at least one object is hovering over the sensor or touching thesensor.
 15. The method according to claim 1, wherein the signalstransmitted to the at least two electrodes are pulsed signals.
 16. Themethod according to claim 1, wherein the signals transmitted to the atleast two electrodes are AC signals.
 17. The method according to claim 1comprising determining a position of the at least one object on thesensor from the signals sampled.
 18. The method according to claim 1comprising detecting more than one object.
 19. An apparatus including asensor sensitive to capacitive coupling comprising: a sensor includingan array of active electrodes and an array of passive electrodes, theactive and passive array forming a grid; a switching apparatus operativeto simultaneously transmit signals on at least two active electrodes,wherein at least one of the signals simultaneously transmitted on eachof the at least two active electrodes has a frequency that is differentfrom a frequency of a signal transmitted on another electrode of the atleast two active electrodes; and sensor electronics configured to samplean output signal on at least one passive electrode crossing the at leasttwo active electrodes, wherein the output signal is responsive tocapacitive coupling formed between the at least two active electrodesand the at least one passive electrode; wherein the output signalprovides information regarding at least one object located on thesensor.
 20. The apparatus according to claim 19, wherein the differentfrequencies are frequencies that are orthogonal to each other.
 21. Theapparatus according to claim 19, wherein the active electrodes aredivided into a plurality of groups, and wherein the switching apparatusis configured to transmit signals to electrodes in each group serially.22. The apparatus according to claim 21, wherein the signals transmittedserially are of a same frequency.
 23. The apparatus according to claim21, wherein the switching apparatus is configured for simultaneouslytransmitting signals to electrodes from different groups, wherein eachof the signals transmitted has a frequency that is different from afrequency of the signals transmitted on electrodes from other groups.24. The apparatus according to claim 19, wherein the signals transmittedto the at least two active electrodes are pulsed signal.
 25. Theapparatus according to claim 19, wherein the signal transmitted to theat least two active electrodes are AC signals.
 26. The apparatusaccording to claim 19, wherein the electrodes are conductive lines. 27.The apparatus according to claim 19, wherein the sensor is substantiallytransparent.
 28. The apparatus according to claim 19, wherein the atleast one object is a body part or a conductive object.
 29. Theapparatus according to claim 28, wherein the body part is a finger. 30.The apparatus according to claim 19, wherein the at least one objectlocated on the sensor is hovering over the sensor or touching thesensor.
 31. The apparatus according to claim 19, wherein the sensorincludes a plurality of junctions formed between the array of activeelectrodes and the array of passive electrodes.